ZNC is an advanced IRC bouncer.

ZNC will remain connected to an IPv4 or IPv6 IRC server even while you
are offline. You can reattach your client at a later time and catch up
with what happened while you were gone via the history buffer. You can
add additional users under one running process, useful for public shells
that limit background processes. ZNC also supports the dynamic loading
of C++ and Perl modules.

The SlackBuild file for ZNC includes support for OpenSSL connections
to IRC servers.  If you do not wish to include OpenSSL support in ZNC, 
simply run the build script like this:
  WITH_SSL=no ./znc.SlackBuild

IPv6 support is also enabled by default; to disable it, run the script
like this:
  WITH_IPV6=no ./znc.SlackBuild

This is intended to be run as a nonprivileged user - by default, the
build script uses "znc" as the user.  If you wish to change it, e.g. 
to use the "nobody" user, then run the script as follows:
  ZNC_USER=nobody ./znc.SlackBuild

See README.SLACKWARE for configuration information.
